Nuclear medicine imaging modalities such as single photon emission computed tomography (SPECT) and positron emission tomography (PET) are powerful, non-invasive medical imaging techniques that provide an image of the three dimensional distribution of a radionuclide in any slice through an organ under study in the body [Phelps]. These images allow investigation of metabolism in the region being studied and are a useful tool for understanding the functioning of the organs as well as diagnosing symptoms of diseases. Nuclear medicine is a very important modality in cardiac imaging, providing both diagnosis as well as prognosis. SPECT is commonly used in localizing coronary artery disease and as many as 90% of myocardial perfusion studies are now performed using SPECT. The role of PET in cardiac imaging is gradually expanding, particularly in the areas of detecting coronary artery disease (where it shows -10 to 15% higher accuracy then SPECT) and assessing myocardial viability [Gunn Bronson]. Recent developments in combining nuclear medicine with X-ray CT imaging provide better attenuation correction in cardiac imaging studies. It is clear that nuclear medicine technologies are playing a prominent and an increasingly important role in cardiac care and clinical diagnosis. However, there is urgent need for improvement in the performance of these imaging modalities in order to exploit their full potential. The goal of the proposed effort is to investigate a new high resolution detector for nuclear medicine. [unreadable] [unreadable]